Identification of the Muscarinic Acetylcholine Receptor Subtype Mediating Cholinergic Vasodilation in Murine Retinal Arterioles

To identify the muscarinic acetylcholine receptor subtype that mediates cholinergic vasodilation in murine retinal arterioles.Muscarinic receptor gene expression was determined in murine retinal arterioles using real-time PCR. To assess the functional relevance of muscarinic receptors for mediating vascular responses, retinal vascular preparations from muscarinic receptor-deficient mice were studied in vitro. Changes in luminal arteriole diameter in response to muscarinic and nonmuscarinic vasoactive substances were measured by video microscopy.Only mRNA for the M(3) receptor was detected in retinal arterioles. Thus, M(3) receptor-deficient mice (M3R(-/-)) and respective wild-type controls …